Car-door signal system.



' J." F. McELROY.

CAR DOOR SIGNAL SYSTEM. APPLICATION FILED. JULY 8. I914.

INVEST H ATTY.

Patented Feb. 22, 1916.

- UNITED STATES PATENT omen.

JAMES F. meELnoY; or ALBANY, NEW YORK, ASSIGNOR 'ro CONSOLIDATED can. j

HEATING COMPANY, A CORPORATION or WEST VIRGINIA.

Specification'of Letters Patent.

Application filed Jul 8, 1914. Serial No. 849,657.

T 0 all whom it may concern:

Be it known that I, JAnEs F. MoELRoY, a citizen of the United States, residing at Albany, county of Albany, State of New York, have invented certain new and useful Improvements in Car-Door Signal Systems, the following being a' full, clear, and exact disclosure of the one form of my invention which I at present deem preferable.

For a detailed description of the present form of my invention, reference may be had to the following specification and to the acthrough the several .cars-ofa train. The

train may contain any desired number of cars although but two are represented in Fig. 1. -The line-wire will, however, serve equally well if it extends through only a single car. At each end of each car, the linewire A is connected to a switch B whichhas three positions corresponding to the three contacts 1, 2 and 3 respectively. a In its first position switch 13 nGQnnects with the trolley, which then serves as a source of current-supply for the line-wire, being con netted thereto througha resistance R. In its second position the switch B leaves its linewire branch open-ended. In its third position the switch connects with 'a' signal S,-the opposite terminal of .whichis-grounded. The switch B which is at therear end of the car or train will be turned to connect with the trolley, while that one at the head of the train will be turned to connect with signal S, the opposite terminal of which is grounded. The intermediate switches B,in the case of a train containing two or more cars, will be left open-ended. That disposi tion' of the switches B is clearly indicated in Fig. 1 of the drawing.

From line-wire A a branch wire goes to each of the respective doors of the car or train and is normally open at the door, so

long as the door is closed, but is arranged to be closed when the door is opened. In Fig. 2 the door branch is shown as coming to the switch-lever 4, which is normally held away 'tion of the signal.

from the corresponding contact 4 so long as the'door E is closed, but brought, by spring D, into engagement therewith to close the circuit when the door is opened, thereby connecting the door branch to ground.

It is manifest that when all the doors are closed, the current from the trolley will go from the rear of the. car or train through line-wire Ato the signal S at the head of the car or train and so maintain the signal in its normal energized condition. If, however, a single door is open, it will close its ground-branch and thereby short-cir- Patented Feb. 22, 1916.

cuit the signal S and cause it to be ex- 1 tinguished, giving notice to the motorman that a door'is open. Likewise, if the linewire A becomes grounded by accident, as is liable to happen, itwill, in a similar way, cause the extinction-of the signal. The source of supply is connected to wire A at the rear of the train in. order that, if the train should break in two, it would cut-off the source'of current and cause the extinc- Another advantage of my system is that it; requires but a single line-wire and a single branch-wire there-' from at each car-door. Another advantage is the elimination of the trouble, frequently encountered, of the failure of the motorman toturn the right connecting-up switch on a' train, with the result that the system, while apparently working -rightly,cwill in fact be I disconnected 1 from thedoors in one half or more of the cars of a train, and so be 1maifected by. the opening or closure of such disconnected doors." In my system that cannot'occur, foreven if. the .motormanturns one of the intermediate switches B (instead of therear switch B').;.to.its trolley-connection, the doors of the entire train will still maintain-control of the signal.

What I claim as new and desire to secure by Letters Patent is:

1.. In a car door signal, the combination with a line wire, and groundconnections therefor, of fa. source of current supply,

.means at one'end of said .line wire to selectively close the circuit to said source of power, or to saidground -connections, a signal in each ofthe ground connections, and normally open ground branches from said line wire corresponding to and controlled by the respective doors of the car.

2. In a car-door signal system, the combination with a line-wire in the car, of a source of current-supply therefor, a grounded signat, branch-wires extending to the several doors of the car, and means for grounding each of said branches on the opening of the corresponding door.

3. In a car-door signal systennthe combination with a line-wire in the car, of a source of current-supply therefor, a normally-energized signal in a grounded branch of said line-wire, and normally-open groundbranches for each door adapted to be closed by the opening of the corresponding door.

4. In a car-door signal system, the combination with a line-wire in the car, a source of current-supply connected thereto at one end of the car, a normally grounded signal at the opposite end, and normally-open ground branches for the respective doors adapted to be closed on the opening of a door.

5. In a car-door signal system. the combination with a line-Wire in the car, of a source of current-supply and a grounded signal at each end of the car, switches at each end of the car for connecting the linewire to the source of supply at one end and to the grounded signal at the other end, and branch ground-wires controlled by the respective doors of the car.

6. In a car-door signal system. the comtions, one position serving to connect the branch to ground through a signal, another position servingto connect.the branch to a source of current-supply, and. the third position serving to open-end the branch. and a normally open ground-branch from said line-wire extending to each of severalcar-doors of the train and arranged to be closed by the opening of the corresponding door.

In witness whereof I have hereunto set my hand, before two subscribing witnesses. this 6th day of July 1914.

JAMES F MGELROY.

'Witnesses:

HERBERT A. CALKINs, I. A. B. MoELvnNnY. 

